Trouble Starting

Hello everyone, I have a '72 FJ40 that has trouble starting. If I drive it everyday it runs great, but if it sits for a couple of days or is really cold out(which tends to happen here in colorado) it will try to turn it over and then I end up killing the battery because it just wont start or when I turn the igintion key it will just give one solid click. People are telling me its either the alt or starter. Hoping you guys might be able to tell me where to start looking. Thanks in advance

It really doesn't sound like a starter. When starters go bad, they typically have problems when they are warm. Cold is usually the battery. If you have a known good battery, then look for a draw, and/or bad connections. Even a partially bad battery will have problems when it gets good and cold. My 6 mo. old optima red top was unhappy this morning in near 0 degrees after sitting for 2 days.

If it starts good when you drive it every day, it's probably not the alternator either.

That's not to say it can't be the starter, in this case it would be down the list of things I look at first.

The first thing to check is the connection at the battery cables, and the way to do it is loosening the strap bolt and cleaning, brushing or scraping a nice shine on the batt post and the terminal itself. Like Todd said, start with a known good battery, and test from there. If the batt and terminals are good, then you could still have corrosion at the fusible link (if so equipped, it'll be on the pos side about 6" from the terminal) or at the frame attaching point/ ground strap on the neg side. You'd be shocked how many people come to discover one day that the only ground for their vehicles is provided by the choke cable jacket rubbing into the body .
Check your ground strap and wiring for chafing while you're at it. And four pumps on the gas pedal, then crank with your foot off the gas until it catches, then gas/choke as needed.